Complex technical devices today usually have their own internal software. Such devices can generate data that is of interest for the user or for a method for checking the device. Such data may then be read out via optical ports, for example, and forwarded to diagnostic devices. Especially in the field of aviation technology, readout and checking of systems of an airplane by a diagnostic module is extremely important. To do so, for example, a diagnostic module may be connected via an optical bus to the aircraft to perform a diagnostic method with regard to the aviation systems. Various signals may be transmitted from the connected diagnostic module to the aircraft and vice-versa by means of electromagnetic energy.
However, errors may occur in readout, performing the diagnostic method, or loading software. In the past, the state of the art has provided only a port on an aircraft for subjecting the aircraft to a diagnostic procedure by means of optical data transmission. It is impossible here to check the performance while performing the diagnostic procedure as part of maintenance and to forward any errors detected to the user.
So-called 3Y solutions in which three different Y couplers are used between an optical port and a device are known in the state of the art. These are extremely impractical with regard to their dimensions, lengthening the optical path for the signals, significantly increasing damping and causing substantial costs for the manufacturer. This approach from the state of the art also leads to inadequacies when there are great temperature differences.